There were two facial expressions I remember from last year's NBA Finals, and both involved former San Diego State star Kawhi Leonard.

Let's start with the first.

It's Game 5 in San Antonio and the series between the Spurs and the Heat is tied at 2-2. With 2:14 remaining in the first half, the substitution horn sounds, and as LeBron James looks back to the scorer's table, he grimaces as Leonard checks into the game for the Spurs.

Now, there is no way to prove that it was the 22-year-old's presence that caused the four-time MVP to scowl. Some might even argue that James is beyond reacting to anyone stepping onto the same court as him.

But if you were watching that series closely, if you saw how, through those first five games, Leonard was able to reduce the world's greatest basketball player from freight train to mere SUV, then you could understand why LeBron would be peeved.

Here's the simple truth of the matter: Kawhi changes the game. Advanced basketball stats suggest that the 6-foot-7 forward's offensive and defensive efficiency numbers improve every year, and that this season, he was responsible for about 7.7 Spurs wins -- more than anybody on the roster.

Say what you will about geek-generated data vs. the good old-fashioned eye test, but if you wanted to argue that Leonard was the best player on the NBA's best team during the regular season, you wouldn't be alone.

Leonard, of course, would never make that argument. Not just because he's humble, but because in order for one to make an argument, he has to actually talk. Kawhi never really got into the whole...words trend that humans find so groovy, but that's OK -- there have been plenty of people to talk for him.

Perhaps his most noteworthy advocate has been Spurs coach Gregg Popovich, who anointed the third-year player "the future of the Spurs" earlier this week. Popovich made a similar claim after Leonard's rookie season and has looked clairvoyant ever since.

Kawhi's points-per-game and rebounds-per-game averages have increased every year, and finished at 12.8/6.2 this season. His shooting percentage (.522) also keeps going up, as does his 3-point percentage (.379), and his D earned him a spot on the 2013-14 All-NBA Defensive Second Team.

Aside from Tim Duncan, there may not exist a better embodiment of a Spur -- a player who exists to win and nothing more.

Which is why the other facial expression from last year's Finals stood out so much -- the one Leonard displayed after missing a free throw in Game 6.

Quick recap: With 19.4 seconds remaining in the fourth quarter, and the Spurs holding a two-point-lead and a 3-2 advantage the series, Kawhi was fouled and sent to the line for two shots.

When he missed the first one, he looked as though he dropped the Thanksgiving turkey in a mud puddle. It was horror mixed with dejection, and considering that the Heat came back to win the game and the series, you have to think that Kawhi (who did make the second one) has that stroke playing on a loop in his head.

Of course, anyone who understands basketball knows that the loss was not on him. Manu Ginobili missed a free throw less than a minute earlier for the Spurs, and Popovich kept Duncan off the floor on the final possession of the fourth quarter, thus allowing Miami to secure an offensive rebound and send the game to overtime.

Still, with Game 1 of a Heat-Spurs Finals rematch set for tonight, the Kawhi Leonard storyline is particularly intriguing. As SDSU head-coach-in-waiting Brian Dutcher said, "he's seeking a level of perfection. He's never satisfied."

He also could be the difference in this series.

If Leonard plays his game, if he is able to neutralize James like he did last year and contribute his expected level of offense, the Spurs will take their fifth NBA championship. Kawhi, already a top-30 player in the league, could then solidify himself as one of the NBA's elite.